In U.S. Pat. No. 5,547,655, the inventors of the present invention disclose an electrochemical process for recovery and regeneration of sulfuric acid from the spent sulfuric add catalyst of the alkylation of C3-C5 olefins and alkanes by using active intermediates generated by electrolysis, heat and photolysis. Both the organic impurities and water containing in the spent sulfuric acid catalyst are simultaneously removed under mild operating conditions. Over 90% water and 95% organic impurities of its initial value, respectively, are efficiently removed from the spent sulfuric acid catalyst, which avoids the disadvantages of the combustion of the corrosive spent sulfuric acid catalyst at high temperature, the purification and oxidation of SO2 at high temperature in the traditionally commercialized process. In U.S. Pat. No. 5,547,655, the organic impurities in the spent sulfuric acid catalyst are decomposed mainly to CO2 and H2O, and thus it is not a low carbon footprint process.
In U.S. Pat. No. 5,888,920, the inventors of the present invention disclose a continuous integrated process for in situ regenerating sulfuric acid from an alkylation unit and recycling the regenerated sulfuric add as a catalyst to the alkylation unit. Similar to U.S. Pat. No. 5,547,655, the organic impurities in the spent sulfuric acid catalyst are decomposed mainly to CO2 and H2O, and thus it is not a low carbon footprint process.